Phytoliths and paleoenvironment from the archaeological Locality Tapera Moreira (La Pampa province, Argentina).

BERÓN, MÓNICA ALEJANDRA; GABRIELA MUSAUBACH; MARGARITA OSTERRIEH; GEORGINA ERRA

Mar del Plata

Congreso; 7th International Meeting on Phytolith Research y 4th Southamerican Meeting on Phytolith Research; 2008

Society for Phytolith Research-Grupo de Estudios Fitol¨ªticos Aplicados del Cono Sur

In this paper we present preliminary results of paleoethnobotany studies performed in the Archaeological Locality Tapera Moreira. This Locality is located at 38¡ã 33¡ä LS and 65¡ã 33¡ä LW, on the Curac¨® River Basin, Lihue Calel District, La Pampa Province, Argentina. The excavations carried out in the Locality allowed us to establish a chronological-cultural sequence that begins 4600 years BP and spreads up to pre-Hispanic moments. Five archaeological sites were identified there (Sites 1 to 5), on the basis of the topographic differences of their emplacement and the characteristics of the archaeological materials present in each of them. The material consists of 17 total mineralogical fraction samples, corresponding to the sedimentary column of the north profile of the Site 1. The sediment of the sequence is typically frank-sandy to sandy-frank, with typical mineralogy of re-worked loess by fluvioaeolic action. The presence of phytoliths is considerable with varied morphologies in all the sedimentary levels. Among the macrophytoliths there were, elongates, bulliform, hair base and unciform hair cells. The short grass cells phytoliths appear in minor proportion, among them, rondels, conical, trapeziform and bilobates -panicoid, simple and Stipa type-. It is remarkable the presence of saddle, typical Chloridoid phytolith, of metabolic route of 4 carbons (C4), especially in the mid and low levels. A notable change in the mineralogical variability respect of the superjacent levels is observed in the samples F17 and F18 corresponding to the levels XXXI and XXXII of the cultural and sedimentary sequence. They are enriched in volcanic ashes of all the sizes (from thick sand to fine lime). Simultaneously, a remarkable lack of cultural evidence characterized the sedimentary levels corresponding to these samples. The presence of a great quantity of articulated phytoliths in big fragments (> to 100 ¦Ìm) it is extremely interesting in the sample F18 (corresponding to 3,85 m). In addition, the articulated phytoliths still have organic not carbonized remains. This information is relevant in relation to the macroregional level where a wide archaeological hiatus has been dated in the Middle Holocene. This hiatus appears almost simultaneously in the south of Mendoza (7500-4000 years BP), center of La Pampa (6500-5000 years BP) and south of Buenos Aires (5960-5060 years BP) provinces, but in different ranges. Several authors have attributed this hiatus to the effects of volcanism. The hiatus raised for La Pampa represents the previous moment in which the locus of the Tapera Moreira began to be in constant use. Though these results are preliminary, they offer paleoenvironmental information on the region in study, thus providing useful tools to do inferences in man-environment relationship.